Field of the Invention
The present invention relates generally to methods and systems for production of hydrocarbons and/or other products from various subsurface formations such as hydrocarbon containing formations.
Description of Related Art
Hydrocarbons obtained from subterranean formations are often used as energy resources, as feedstocks, and as consumer products. Concerns over depletion of available hydrocarbon resources and concerns over declining overall quality of produced hydrocarbons have led to development of processes for more efficient recovery, processing and/or use of available hydrocarbon resources. In situ processes may be used to remove hydrocarbon materials from subterranean formations that were previously inaccessible and/or too expensive to extract using available methods. Chemical and/or physical properties of hydrocarbon material in a subterranean formation may need to be changed to allow hydrocarbon material to be more easily removed from the subterranean formation and/or increase the value of the hydrocarbon material. The chemical and physical changes may include in situ reactions that produce removable fluids, composition changes, solubility changes, density changes, phase changes, and/or viscosity changes of the hydrocarbon material in the formation.
Oil shale formations may be heated and/or retorted in situ to increase permeability in the formation and/or to convert the kerogen to hydrocarbons having an API gravity greater than 10°. In conventional processing of oil shale formations, portions of the oil shale formation containing kerogen are generally heated to temperatures above 370° C. to form low molecular weight hydrocarbons, carbon oxides, and/or molecular hydrogen. Some processes to produce bitumen from oil shale formations include heating the oil shale to a temperature above the natural temperature of the oil shale until some of the organic components of the oil shale are converted to bitumen and/or fluidizable material.
U.S. Pat. No. 3,515,213 to Prats, which is incorporated herein by reference, describes circulation of a fluid heated at a moderate temperature from one point within the formation to another for a relatively long period of time until a significant proportion of the organic components contained in the oil shale formation are converted to oil shale derived fluidizable materials.
U.S. Pat. No. 5,392,854 to Vinegar et al. discloses a process to produce hydrocarbons from diatomite or oil shale formations where production wells are provided, and completed with fractures. Rows of heaters are provided with the rows being parallel to the fractures of the production wells.
U.S. Pat. No. 7,562,707 to Miller and U.S. Pat. No. 7,635,024 to Karanikas, both of which are incorporated herein by reference, describe methods and heaters for treating a hydrocarbon containing formation that includes providing heat from a plurality of heaters to mobilize hydrocarbons in the hydrocarbon formation.
U.S. Pat. No. 7,798,220 to Vinegar et al.; U.S. Pat. No. 7,717,171 to Stegemeier; U.S. Pat. No. 7,841,401 to Vinegar et al.; U.S. Pat. No. 7,739,947 to Stegemeier et al.; U.S. Pat. No. 7,681,647 to Mundunuri et al.; U.S. Pat. No. 7,677,314 to Hsu; U.S. Pat. No. 7,677,310 to Vinegar et al.; and U.S. Pat. No. 7,673,681 to Vinegar et al., all of which are incorporated herein by reference, describe methods for treating hydrocarbon formations that include heating hydrocarbons layers with heaters in combination with a drive and/or oxidizing fluid.
Production of the liquid hydrocarbons from a liquid hydrocarbon containing formation can be problematic when formation containing the liquid hydrocarbons does not have a natural recharging system. When a hydrocarbon containing formation contains gas, the gas could provide a natural recharging system because when some of the hydrocarbons in the formation are removed, the pressure within the formation would decrease, and any gas in the formation would expand. Thus, hydrocarbons is such a formation could be produced.
Other natural recharging systems might include communication with an aquifer wherein brine or water could displace any removed hydrocarbons, and pressure within the formation would be maintained. Without a natural recharging system, production of liquid hydrocarbons is problematic. When a product well is drilled and completed within such a formation, some liquid hydrocarbons will drain into the production well, and could be produced, but after five to eight percent of the liquid hydrocarbons present are produced, the lack of a force to drive the hydrocarbons into the production well bore results in extremely slow subsequent production. The small recovery of liquid hydrocarbons may not justify production of oil from such formation.
Some light tight oil formations do not contain sufficient gas to drive the oils to production wells, and these formations are generally considered to not be economically producible. In general, at least a gas content of fifteen percent by volume of pore space in a light tight oil formation is considered to be necessary for the formation to be producible by existing methods.
As discussed above, there has been a significant amount of effort to produce hydrocarbons from hydrocarbon containing formations. At present, however, there are still many hydrocarbon containing formations that cannot be economically produced. Thus, there is a need for improved methods for heating of a hydrocarbon containing formation that contain kerogen or hydrocarbons and production of liquid hydrocarbons having desired characteristics from the hydrocarbon containing formation are needed.